Inkjet Head Driving Device Randomizes Droplet Timing
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Solution Overview
Problem
Inkjet recording apparatuses face challenges in achieving uniform ink ejection from nozzles, leading to density and color unevenness due to disparities in ink amounts, which increases production costs and visibility of printing errors.
Innovation Solution
A driving device for inkjet heads with multiple ejection channels, featuring driving waveform generation circuits, random number generation, and connection portions to generate and correct driving signals, ensuring pseudorandom correction data is supplied to each channel, thereby randomizing ink droplet formation and minimizing regularity in ink ejection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If very high processing accuracy is required for each nozzle element to achieve uniform ink ejection, then printing quality is improved, but product costs increase
Solution Approach 1:
The patent changes the parameter of driving waveforms by introducing random variations in ejection timing and duration for each nozzle. This allows nozzles with manufacturing variations to produce uniform ink dot densities by compensating through adjusted driving parameters rather than requiring precise manufacturing tolerances.
Solution Approach 2:
The patent measures the actual ink dot density produced by each nozzle and creates a correction map that copies and applies compensation values to all driving waveforms for that nozzle. This allows systematic correction of manufacturing variations without reworking individual nozzles.
2Reliability
If uniform ink ejection from each nozzle is demanded to avoid density unevenness, then printing quality is improved, but manufacturing complexity increases
Solution Approach 1:
The patent performs preliminary measurement of each nozzle's ink ejection characteristics during or after manufacturing, and pre-calculates correction values that are stored and applied during normal operation. This preliminary characterization simplifies ongoing manufacturing by providing a systematic correction approach rather than requiring complex real-time control.
Solution Approach 2:
The patent implements a feedback mechanism where the actual ink dot density is measured and used to generate correction waveforms that compensate for nozzle variations. This feedback loop allows the system to automatically adjust for manufacturing variations without increasing physical manufacturing complexity.
3Manufacturing precision
If correction waveforms are generated based on measured ink amounts to compensate for nozzle variations, then density unevenness is reduced, but processing time increases
Solution Approach 1:
The patent performs ink ejection measurements and generates correction waveforms in advance, before actual printing operations. This preliminary correction process allows the system to store optimized driving waveforms that compensate for nozzle variations, eliminating the need for time-consuming real-time measurements during production printing.
Solution Approach 2:
The patent implements periodic measurement and correction cycles where nozzle characteristics are characterized at scheduled intervals, and correction maps are updated accordingly. This periodic approach balances the need for accurate correction with production time constraints by not requiring continuous measurement during all printing operations.
Data Source
AI summary
A driving device of an ink jet head including a plurality of ejection channels, including a plurality of driving waveform generation portions that are provided which respectively correspond to the plurality of ejection channels, a random number generation portion that generates a random number, and a connection portion. The driving waveform generation portions receive printing data and correction data, generate a driving signal of the ejection channels on the basis of the received printing data, correct a waveform of the driving signal by using the received correction data, and then output the corrected waveform to the correction data and to the corresponding ejection channels. The connection portion connects the random number generation portion of the driving waveform generation portions such that a random number is supplied to each of the driving waveform generation portions as correction data having a value independent for each of the driving waveform generation portions.